1. Field of the Invention
The present invention relates to a switch device, and, more particularly, to a switch device which is suitable for use in driving a mirror of an automobile.
2. Description of the Related Art
The switch device is used for remotely controlling a mirror which is mounted to, for example, the body of an automobile from the driver""s seat by the driving power of a motor. In addition, the switch device is used to selectively operate a plurality of switches which are disposed inside a case by pressing an operating section which is rockably stopped at the top portion of the case.
A description of a conventional switch device is given with reference to the relevant drawings.
FIG. 14 is an exploded perspective view of a conventional switch drive. FIG. 15 is a sectional view of the conventional switch device.
As shown in FIG. 14, the conventional switch device comprises a case 21 having an open bottom end and a cover 29 for covering the open end of the case 21. The case 21 and the cover 29 are snappingly coupled together, whereby the external shell of the switch device is formed.
A printed wiring board 28 having three stationary contacts 28a formed thereon is placed on the cover 29. Three sliding members 25 having corresponding movable contacts 27 affixed thereon are placed above the corresponding stationary contacts 28a which are formed on the printed wiring board 28, with each of the movable contacts 27 being disposed so that it can come into contact with and separate from its corresponding stationary contact 28a by sliding.
The three stationary contacts 28a which are formed on the printed wiring board 28 and the three sliding members 25 which have the corresponding movable contacts 27 affixed thereto form three switches.
A substantially square recess 21a is formed in the top surface of the case 21. Clearance holes 21b are formed in three of the four corners of the recess 21a. 
A protruding wall 21d having a through hole 21c is formed in the center of the recess 21a. 
Three actuating members 22 are provided, each of which comprises a circular cylindrical base 22a and substantially semicircular ends 22b which are provided on both ends of its corresponding base 22a. 
A rubber spring 23 comprises a flat, substantially rectangular base 23a, substantially dome-shaped spring sections 23b-1, 23b-2, 23b-3, and 23b-4, and planar presser sections 23c-1, 23c-2, 23c-3, and 23c-4. The spring sections 23b-1, 23b-2, 23b-3, and 23b-4 are formed on the four corners of the base 23a, respectively. The presser sections 23c-1, 23c-2, 23c-3, and 23c-4 have circular cylindrical shapes, are formed on ends of the corresponding spring sections 23b-1, 23b-2, 23b-3, and 23b-4, and have their ends formed parallel to the base 23a, that is, in a horizontal direction.
The spring sections 23b-1, 23b-2, 23b-3, and 23b-4 function as what are called buckling sections.
A rectangular through hole 23d is formed in the center of the base 23a. An inside wall 23e is formed on the base 23a in a standing manner so as to surround the peripheral portion of the through hole 23d. 
All of the four spring sections 23b-1, 23b-2, 23b-3, and 23b-4 which function as buckling sections have the same wall thicknesses L3 (such as approximately 0.6 mm). Therefore, the click ratios of the four spring sections 23b-1, 23b-2, 23b-3, and 23b-4 are individually the same.
The rubber spring 23 is accommodated inside the recess 21a of the case 21. At this time, the actuating members 22 are in contact with the inside walls of the three corresponding presser sections 23c-1, 23c-2, and 23c-3, and are disposed so as to be slidable inside their corresponding clearance holes 21b in the case 21. The presser section 23c-4 is not provided with an actuating member. The through hole 23d in the rubber spring 23 is disposed so as to oppose the through hole 21c in the case 21.
As shown in FIG. 15, an operating member 24 is formed of, for example, a synthetic resin material by molding. The operating member 24 comprises a substantially rectangular top wall 24a, side walls 24b which extend in a substantially vertical direction from the peripheral ends of the top wall 24a so as to surround the peripheral end portions of the top wall 24a, and four cylindrical actuating sections 24c which are cross-shaped in cross section and which protrude inwardly from the vicinity of the four corresponding corners of the top wall 24a. 
An end surface of each actuating section 24c of the operating member 24 is formed with the same predetermined tilt angle al (such as approximately three degrees) with respect to the top wall 24a (that is, the horizontal plane). Each end surface extends radially outward from substantially the center of the operating member 24.
A description of the operation of the switch device will now be given.
As shown in FIG. 14, when, for example, the operator presses substantially the center portion of the lower left end side of the operating member 24 shown in FIG. 14 with, for example, his/her finger (not shown), the operating member 24 tilts to the lower left side. When the operating member 24 tilts to the lower left side, the two left actuating sections 24c and 24c of the operating member 24 are pushed downward. When these two left actuating sections 24c and 24c are pushed, the corresponding presser sections 23c-1 and 23c-2 of the rubber spring 23 which have been brought into contact with the two left actuating sections 24c and 24c are pushed downward.
When each of the presser sections 23c-1 and 23c-2 of the rubber spring 23 is pushed, each of the spring sections 23b-1 and 23b-2 buckles as the operator is provided with a tactile feel, so that the operator is provided with a proper tactile feel. At this time, the presser sections 23c-1 and 23c-2 cause the two actuating members 22 which are in contact with the inside walls of their corresponding presser sections 23c-1 and 23c-2 to be pushed and to slide downward.
When these two actuating members 22 slide downward, the ends 22b of each of these actuating members 22 move downward on inclined portions 25c of the two corresponding sliding members 25. Here, these two sliding members 25 slide, along with their corresponding movable contacts 27, above the corresponding stationary contacts 28a which are formed on the printed wiring board 28 so as to go against the resilient forces of corresponding coil springs 26.
When these two sliding members 25 slide, each of the corresponding movable contacts 27 comes into contact with its corresponding stationary contact 28a, so that two switches are brought into an on state.
Next, when the operator moves his/her finger off the operating member 24, the resilient forces of the two corresponding coil springs 26 cause the two corresponding sliding members 25 to slide back to their original positions. Here, each of the corresponding movable contacts 27 separates from its corresponding stationary contact 28a, so that the two switches are brought into an off state.
By the sliding of the two sliding members 25, the corresponding actuating members 22 are pushed upward, and the operating member 24 is pushed upward to its original position by the self-restoring force of the rubber spring 23.
As shown in FIG. 14, when the operator presses, for example, substantially the center portion of the upper left end side of the operating member 24 shown in FIG. 14 with, for example, his/her finger (not shown), the operating member 24 tilts to the upper side. When the operating member 24 tilts to the upper side, the corresponding actuating sections 24c of the operating member 24 are pushed downward. When these actuating sections 24c are pushed downward, the corresponding presser sections 23c-1 and 23c-4 of the rubber spring 23 which have come into contact with these actuating sections 24c are pushed downward.
The operations which follow the pushing down of the presser sections 23c-1 and 23c-4 are substantially the same as those when substantially the center portion of the lower left end side of the operating member 24 is pressed, so that the details thereof will be omitted. However, since an actuating member 22 and a switch are not provided below the presser section 23c-4, the one switch which is disposed below the presser section 23c-1 is brought into an on state. Thereafter, the operating member 24 is restored to its original position by the self-restoring force of the rubber spring 23, so that the one switch is brought into an off state.
A description of the clicking characteristics which are provided during the operation of the switch device will be given.
FIG. 16 is a graph illustrating the clicking characteristic which is provided when two switches of the conventional switch device are actuated. FIG. 17 is a graph illustrating the clicking characteristic which is provided when one switch of the conventional switch device is actuated.
As shown in FIG. 16, when two switches are actuated by pushing, for example, the spring sections 23b-1 and 23b-2 at the same time as a result of pushing a predetermined location of the operating member 24 (see FIG. 15) of the conventional switch device, the clicking characteristic represented by Graph C is obtained. Graph C represents the clicking characteristic in which the change in load which occurs when the corresponding spring sections buckle becomes small due to the actuating forces required to actuate two switches.
As shown in FIG. 17, when only one switch is actuated by-pushing, for example, the spring section 23b-1 and the spring section 23b-4 at the same time as a result of pushing a predetermined location of the operating member 24 of the conventional switch device, the clicking characteristic represented by Graph D is obtained. Graph D represents the clicking characteristic in which the change in load is greater than that in Graph C because an actuating force for actuating only one switch is required.
As can be understood from the foregoing description, the conventional switch device exhibits the clicking characteristic shown in either Graph C or Graph D depending on the pressing location (that is, the pressing direction) of the operating member 24, so that a difference in the clicking characteristics occurs depending on the pressing location.
In the conventional switch device, either one or two switches are actuated depending on the pressing location of the operating member. Therefore, the clicking characteristic which is provided when one switch is actuated and that which is provided when two switches are actuated are different, giving rise to the problem that the operator experiences a different tactile feel when operating the operating member.
Accordingly, in order to overcome the above-described problem, it is an object of the present invention to provide a switch device which is uniformly operable as a result of providing a uniform tactile feel regardless of the directions of pressing locations of an operating member which is operated by an operator with, for example, his/her finger.
To this end, according the present invention, there is provided a switch device comprising an operating member which is stopped by a case so as to be rockable in four directions, a rubber spring including four spring sections, one first spring section and three spring sections, and three switches which are disposed in correspondence with the three second spring sections, with the remaining one first spring section not being provided with a switch. The spring sections are disposed at peripheral edges of the operating member inside the case, respectively, with the spring sections being selectively actuated two at a time as a result of rocking the operating member in one direction. In the switch device, the spring sections are actuated and buckled by operating the operating member in order to switch the switches. In addition, a click ratio of the first spring section is greater than click ratios of the second spring sections.
The four spring sections may be disposed at locations which oppose four corners of the operating member, respectively.
When the four spring sections are disposed at locations which oppose four corners of the operating member, respectively, each spring section may comprise a buckling section, and a wall thickness of the buckling section of the first spring section may be greater than wall thicknesses of the buckling sections of the second spring sections.
When the four spring sections are disposed at locations which oppose four corners of the operating member, respectively, each spring section may comprise a buckling section, and a tilt angle of the buckling section of the first spring section with respect to the case may be greater than tilt angles of the buckling sections of the second spring sections with respect to the case.
When the four spring sections are disposed at locations which oppose four corners of the operating member, respectively, the click ratio of the spring section which is greater than the click ratios of the three other spring sections may be approximately 50%, and the click ratios of the three other spring sections may be approximately 33%.
When the four spring sections are disposed at locations which oppose four corners of the operating member, respectively, the operating member may be resiliently biased by the spring sections, the operating member being stopped at the case by a resilient force thereof.
When the four spring sections are disposed at locations which oppose four corners of the operating member, respectively, each switch may comprise a printed wiring board which is, disposed inside the case, a stationary contact which is formed on its corresponding printed wiring board, a slider which slides above its corresponding printed wiring board, and a movable contact which is disposed at its corresponding slider. In each switch, each slider slides by its corresponding spring section in order to switch its corresponding switch.